Unitized seals are well known in the prior art and generally comprise radially inner and outer metal casings which are nested together and spaced radially from each other to create a generally annular sealing space therebetween. The casings do not touch, but a seal located between the casings seals the space. The unit may be separately handled and press fit between a shaft and bore or between the races of a radial bearing. Such seals generally include a garter spring type seal for wear take-up of the sealing lip. This can create excessive torque in a radial bearing of relatively large diameter such as may be found in a radial bearing large enough to fit over a CV joint. While unsprung unitized seals exist in the art, they are not well suited for the application desired. Such bearing applications, especially in automotive wheel bearings, involve high temperatures and pressures which it may be necessary to vent, as well as the necessity of excluding contaminants such as water and particulates.
The U.S. patent to Bernstein, U.S. Pat. No. 2,240,252, discloses an unsprung unitized oil seal interposed between a shaft and a bore. Oil seals are not, in general, particularly applicable to the very different task of a grease seal in the environment of a wheel bearing. The structure in Bernstein includes too many surfaces in rubbing contact to run with sufficiently low torque. The U.S. patent to Huddle, U.S. Pat. No. 3,101,954, discloses a structure suitable to heavy farm machinery and designed to allow heavy particulates to wedge between the casings to more tightly bias a sealing lag. Such a design would not be suitable in a higher speed automotive application, as the torque would be far too high. The UK Patent Application GB No. 2 107 024A discloses an unsprung unitized seal in an over CV application. However, the design appears to comprise a single casing which would rub between the bearing races as they rotated relative to one another to create an extremely high torque.